Spatial distribution of groundwater nitrate nitrogen in the agricultural area of Shandong Province

Under the guidance of the optimal stratified sampling frame in which spatial distribution is consistent with the random sampling principle, this paper takes the groundwater nitrate nitrogen pollution in the intensive cropping area in Shandong Province as the object of study, and collects 548 groundwater nitrate nitrogen samples of Shandong province from November 2009 to February 2010. The result indicates that the pollution is quite serious, and 46.7% of samples exceeds 11.3mg /l, the maximum allowable value of the World Health Organization (WHO) on drinking water nitrate content. By analyzing the impact of factors such as soil texture, organic content, modulus of groundwater resources, and agricultural planting structure on groundwater nitrate nitrogen contents, we believe that there is an obvious spatial distribution law of the nitrate nitrogen pollution in Shandong Province. Groundwater nitrate nitrogen contents change consistently with the change of agricultural planting structure and spatial pattern of groundwater. The higher the input of fertilizer and the slower the water cycle is, the more serious the pollution will be. From east to west, groundwater nitrate nitrogen contents in Shandong Province can be divided into high- content area, medium-content area and low-content area with the nitrate nitrogen contents of 36.39, 18.10 and 5.17mg/l respectively. The KRIG method of statistics is used to make spatial interpolation, with the interpolation accuracy up to 83.6%, which lays a solid foundation for the further analysis and forecast of the groundwater nitrate nitrogen pollution of Shandong province. Generally, properly changing the agricultural planting structure, reducing the use of the nitrogen fertilizer and improving the utilization efficiency of nitrogen fertilizer is one of the main methods to reduce groundwater nitrate nitrogen pollution in the study area.